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Lime-The Foundation of Soil Health

When you are in the combine this fall you may notice that certain parts of the field yield differently than others. There are a lot of factors that may be at play, but one important thing to assess is the soil pH. The proper pH level is the foundation for healthy, fertile soil. Nutrient availability in the soil has a lot to do with pH, so even if there is an adequate supply of fertilizer in the field, it may not be available to the plant. Nitrogen, Phosphorus, and Potassium are three essential nutrients affected by pH that plants take up in large quantities. Sulfur, Boron, Zinc, Calcium, and Magnesium are a few essential nutrients affected by pH that plants take up in smaller quantities.

Let’s focus on one of these important nutrients in particular. Phosphorus is responsible for seedling vigor and early growth, promotes root development, improves drought and cold stress resistance, and ends up being a major component of grain yield. This essential macronutrient gets tied up in acidic soils and becomes unavailable to the plant. Even in high phosphorus environments, if the pH is too low you may see poor stands of alfalfa, wimpy looking soybeans, and stunted corn plants.

Soil pH is not only important for nutrient availability; it also influences other factors that lead to improved soil health. For example, a neutral pH increases the microbial activity in the soil required for nitrogen fixation and recycling nutrients from crop residue breakdown. Also, pH plays a big role in weed control as well. Certain crop protection products have increased efficacy in neutral soils versus acidic soils.

What is the proper pH?The optimum pH for the common crops in SE MN is 6.8. Corn and soybeans like to be in the 6.0-7 range while alfalfa prefers 6.5-7. This chart from the University of Minnesota shows nutrient availability to plants related to soil pH.

What factors cause low pH?Here are two factors that lower the soil’s pH that can be managed. First is the practice of harvesting and removing crop material such as forages. The second factor has to do with the nitrogen cycle. Whether it is from applied commercial fertilizer, nitrogen fixation by bacteria, or decomposing organic matter, nitrogen leaving the soil lowers pH. This reaction to these common occurrences in agriculture production, as well as other causes not mentioned in this article, can easily be offset by applying ag lime.

How do I raise or maintain a good pH? According to Iowa State University research, liming acidic soils results in a 5% corn and soybean yield increase. Every field and farm is different when it comes to lime requirements, so talk to your All American Co-op agronomist about what is right for your operation. Ag lime is a multi-year investment, so don’t feel like it needs to be all or nothing in one application. We can work with you to maximize your investment by making variable rate applications, selecting fields that will give the highest response, and tailoring a custom recommendation based on your budget and soil needs. If you are concerned about leased land, talk to your land owner about a pro-rated lime reimbursement contract. It is also in their best interest to have good soil health.

Today, as a producer, it is vital to maximize your yields while getting the most return from your investments. Having a balanced soil pH will help all your inputs, from seed to fertilizer to weed control, achieve peak performance.

As one of the newer members of the All American Co-op Agronomy team, I would like to take this opportunity in my first Cooperative Link article to thank you for your continued patronage. It has been my pleasure to meet and work with the St. Charles area members I have come to know since starting my career in February and I look forward to getting to meet more new faces now that I am in Elgin. Growing up 6 miles west of Elgin and farming with my family makes me feel blessed and excited to be able to serve the community that I have known and loved my entire life.